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Macs seized by porn Trojan

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Miscreants have released a sophisticated Trojan into the wild that targets Mac users, according to Intego, a company that markets security software that runs on OS X.

The malicious Trojan, dubbed OSX.RSPlug.A, is making the rounds on several porn websites. When Mac users try to view some videos, the site feeds them a page that says QuickTime is unable to play the file unless a special codec is installed first. If the user proceeds, a form of DNSChanger is installed that hijacks some web requests sent to eBay, PayPal and some banking websites, according to this write-up from Intego.

"The noteworthy part is that someone is targeting the [Mac] OS," said Randy Abrams, a security researcher at antivirus software provider Eset. "This may mean that the OS is beginning to gain enough users to be attractive to attackers."

The Trojan installs a root crontab that makes minute-by-minute queries to check that the doctored DNS server is still active. The websites offer different versions of the malware, most likely to tailor web spoofing to the victim's particular country. There is no way for victims running 10.4 to see the changed DNS server in the OS X GUI. In 10.5, the DNS server is visible in the Advanced Network preferences, but the added servers are dimmed and can't be removed manually.

Apple PR representatives didn't respond to an email seeking comment for this story.

A barrage of spam posted to Mac forums invites readers to visit the malicious websites. The Trojan requires victims to enter the administrative password for their machine, a factor that is likely to mitigate the risk somewhat. Then again, Windows users have for years been tricked into installing malware that can wreak havoc on their PCs. We see no evidence that Mac users are any more resilient to social-engineering attacks. ®